Configurable triple wavelength semiconductor optical amplifier fiber laser using multiple broadband mirrors

A configurable, triple wavelength fiber laser based on broadband mirrors (BBMs) and an arrayed waveguide grating (AWG) is demonstrated. The laser uses a semiconductor optical amplifier (SOA) as the primary gain medium due to its inhomogeneous broadening property that allows for the generation high intensity lasing wavelengths. The combination of the AWG and BBMs allows for triple lasing wavelength outputs with channel spacing from 0.8 to 4.0 nm to be obtained. The generated output is adjustable between 1540.6 and 1548.6 nm. The proposed SOA-based system is stable and can be used as a reserve laser source for wavelength division multiplexing systems. © 2019 Wiley Periodicals, Inc

Investigation of potential toxic effects of construction waste runoff collected from illegal dumping site using brine shrimp and zebrafish models

Urbanization results in the increment of construction waste, which eventually contaminate the surrounding environment and affects the ecosystem. This study aimed to investigate the potential toxic effects of construction waste runoff collected from an illegal construction waste dumping site, Kampung Sungai Pelong, Malaysia by using brine shrimp (Artemia sp.) and zebrafish (Danio rerio). The runoff sample collected in January 2018 proceeded with the physicochemical test, heavy metal analysis and bio-toxicity study. Several physicochemical properties (BOD, TSS, NH3-N and NO3-) and heavy metal content (Cu>Cd>Ni>As>Pb>Cr>Hg) of runoff had values significantly exceeding the respective Class IIA Malaysia National Water Quality Standards. No mortality and abnormal swimming behaviour were observed for brine shrimp acute assay, but severely damage appendages and pigmentation were evident. In the zebrafish sub-acute assay, no constant trend of mortality was observed, but abnormal swimming pattern and alterations in gill tissue (cell vacuolation and clubbed tips). The results signify the potential eco-toxicity caused by construction waste runoff and urge the need for long-term toxicity study and strict legislative actions by the local authority

Dual layer microstrip reflectarray composed of two stacked arrays with minkowski and square shape radiating element

A dual layer microstrip reflectarray composed of two stacked arrays with Minkowski and square patches of variable dimension is presented. The reflection phase coefficients on the reflector surface is achieved by tuning the dimensions of the patches. This technique is to broaden the bandwidth and to extend the reflection phase range compare to a conventional single layer reflectarray. From the simulation results of a unit cell composed of two stacked arrays of Minkowski and square patch showed that, 415° reflection phase range is achieved and lower insertion loss which is lower than 0.9 dB. Base on the simulated reflection phase coefficient, a dual layer microstrip reflectarray antenna with Minkowski and square radiating shape elements have been design and model using commercially available computer models of CST Microwave Studio. The reflectarray has been constructed using Taconic RF-35 substrate. From the radiation pattern at 11 GHz frequency, it shows that the HPBW of 4.7º in both plane, a side lobe level (SLL) of –17 dB and a maximum directivity of 26.1 dBi

Combustion performance of syngas from palm kernel shell in a gas burner

Insufficient and various environmental issues of fossil fuels as the current world dominated energy is now becoming a serious global issue. The rapidly increasing demand for alternative energy sources has contributed to the steady growth of renewable energy. Owing to the fact of the abundant presence of palm kernel shell (PKS) as one of palm biomass wastes in South East Asia region, this paper investigates syngas produced from gasified PKS. The investigation is regarding its composition and combustion performance in a gas burner system. It covers emissions analysis, temperature profile and flame length. The produced syngas from downdraft gasifier was burned in the combustion chamber in air-rich and fuel-rich combustion conditions. From the experiment, the results showed that the oxidation zone temperature of above 750°C for the downdraft gasifier is suitable for producing syngas. Produced syngas can be classified as pure-carbon monoxide (CO) syngas due to 94.9% CO content with no hydrogen (H2) content and low heating value (LHV) of 10.7 MJ/kg. The wall temperature profiles for burnt syngas produced via downdraft gasification was higher with longer pattern at fuel-rich condition, which signified higher energy of syngas produced from downdraft gasifier compared to fluidised bed gasifier. The associated flame length was also longer at fuel-rich condition. Produced emission of 56 ppm NOX, 37 ppm CO and 1 ppm SO2 can still be considered as acceptable to human. It can be concluded that syngas produced from PKS shown a high potential to serve as an alternative source of energy due to its high energy content

Multiwall carbon nanotube polyvinyl alcohol-based saturable absorber in passively Q-switched fiber laser

In this work, we demonstrated a compact Q-switched erbium-doped fiber laser capable of generating high-energy pulses using a newly developed multiwall carbon nanotube (CNT) polyvinyl alcohol (PVA) thin film based saturable absorber. Q-switched pulse operation is obtained by sandwiching the thin film between two fiber ferrules forming a saturable absorber. A saturable absorber with 1.25 wt. % of PVA concentration shows a consistency in generating pulsed laser with a good range of tunable repetition rate, shortest pulse width, and produces a high pulse energy and peak power. The pulse train generated has a maximum repetition rate of 29.9 kHz with a corresponding pulse width of 3.49 μs as a function of maximum pump power of 32.15 mW. The maximum average output power of the Q-switched fiber laser system is 1.49 mW, which translates to a pulse energy of 49.8 nJ. The proposed method of multiwall CNT/PVA thin film fabrication is low in cost and involves uncomplicated processes

Tunable single stokes extraction from 20 GHz Brillouin fiber laser using ultranarrow bandwidth optical filter

The individual extraction of a Brillouin Stokes line from a 20 GHz comb generated from the compact configuration of a multiwavelength Brillouin fiber ring laser configuration has been achieved using an ultranarrow bandwidth (UNB) optical filter. The narrowest bandwidth transmission of a UNB optical filter that is 50 pm is used in order to get particular Stokes. The Stokes filtered is in the wavelength range of 1549.768–1551.016 nm. High SNR within the range of 54.97–11.73 dB with almost nil peak power loss being obtained was monitored by a 0.16 pm optical spectrum analyzer, giving convincing results. Relatively, the proposed configuration could provide wide tunability and narrow selection of the Brillouin Stokes. © 2014 Optical Society of Americ

Supercontinuum generation from a sub-megahertz repetition rate femtosecond pulses based on nonlinear polarization rotation technique

A means of supercontinuum (SC) generation is proposed and demonstrated, using femtosecond mode-locked pulses with sub-megahertz repetition rate based on the nonlinear polarization rotation technique. Total cavity length is approximately 522 m, which includes an additional 500 m single mode fiber (SMF) and the fundamental repetition rate obtained is 404.5 kHz. The mode-locked spectrum has a central wavelength of approximately 1600 nm and a 3 dB bandwidth of 16 nm, which falls within the L-band region. The threshold power for the mode-locked operation is achieved at approximately 52 mW. At pump power of 74 mW, the measured pulse width, pulse energy, and average output power are 70 fs, 18.3 nJ and 7.4 mW respectively. The generated pulses are amplified by a 72.44 mW erbium-doped fiber amplifier before being injected into a 100 m long highly non-linear fiber as the nonlinear medium to generate the SC spectrum. The obtained SC spectrum spans from 1250 nm to more than 1700 nm, with bandwidths of 450 nm at a −70 dBm output power level. For comparison purpose, the 500 m SMF is removed from the setup and similar measurements are then repeated for this case

Graphene-PVA saturable absorber for generation of a wavelength-tunable passively Q-switched thulium-doped fiber laser in 2.0 μm

Graphene, a 2D material, has been used for generation of pulse lasers due to the presence of its various fascinating optical properties compared to other materials. Hence in this paper, we report the first demonstration of a thulium doped fiber laser with a wavelength-tunable, passive Q-switched output using a graphene-polyvinyl-alcohol composite film for operation in the 2.0 µm region. The proposed laser has a wavelength-tunable output spanning from 1932.0 nm to 1946.0 nm, giving a total tuning range of 14.0 nm. The generated pulse has a maximum repetition rate and average output power of 36.29 kHz and 0.394 mW at the maximum pump power of 130.87 mW, as well as a pulse width of 6.8 µs at this pump power. The generated pulses have a stable output, having a signal-to-noise ratio of 31.75 dB, and the laser output is stable when tested over a period of 60 min. The proposed laser would have multiple applications for operation near the 2.0 micron region, especially for bio-medical applications and range-finding

S-band Q-switched fiber laser using MoSe2 saturable absorber

A passively Q-switched S-band fiber laser using Molybdenum Diselenide (MoSe2) saturable absorber (SA) is proposed and demonstrated. The SA is fabricated by depositing MoSe2 onto two fiber ferrules using the drop-cast method before heating and connecting the two fiber ferrules to form the SA. The passively Q-switched fiber laser designed using the MoSe2 SA has an operational range of 1491.0–1502.0 nm. The output pulse train has a pulse-width ranging from 2.0 μs to 1.0 μs and corresponding repetition rate of between 34.5 kHz and 90 kHz with increasing pump powers, as well as a signal-to-noise of about 35.97 dB. The peak performance of the proposed laser is between 1480.0 and 1490.0 nm, corresponding to the first peak gain region with the S-band

HEALTHY LIFESTYLE INSTRUMENT

The main purpose of this study was to develop an instrument to measure the Healthy Lifestyle among employees of KPTM Ipoh, KPTM Alor Setar, UniSHAMS and Intel Kulim. The sample was collected using self-administered questionnaire from 16 people for our focus group based on our sampling frame design and distributed four instruments for each strata group. The total instrument from the pilot study are 64 instruments. Three (3) constructs of the Healthy Lifestyle Instrument primarily consist of Fitness Wellness, Dietary Wellness and Behavior Wellness. The result of descriptive analysis show that the alpha reliability of the construct items in healthy lifestyle are acceptable. This would be express that the Healthy Lifestyle Instrument be considered reliable. However, in the exploratory factor analysis show that the findings are expanded from three factors to seven factors of employee healthy lifestyle practices. As related to this and previous analysis, we conclude that the Healthy Lifestyle Instrument are valid and reliable. However, this will require full data collection in order to fully validate the instrument. Therefore, the 3 aspects of employee’s healthy lifestyle practices will remain the same as before the test performed. This is due to small sample size in pilot study. The same analysis procedure will be performed using sufficient sample size. However, in term of factor analysis in the main study, the finding of new emerge factors from the previous pilot study will be executed in order to conclude the final factoring involve. Keywords: health, lifestyles, exploratory factor analysi